You can find the 1-hour pass directly on the vehicle card in the app. Simply select a moped in your area and click on "Rate plans".
Under Options you will find the 1h prepaid tariff, which you can ride with as much as you want for one hour for €12.
Important: Please note that you cannot switch between mopeds with the 1-hour pass - with this plan you can only use the selected scooter.